qBittorrent official forums

It may be a bug of sorts, but probably not where you'd expect!

Someone on that torrent may be trying to download it and have a constantly resetting+changing ip address, so the torrent tracker/s and Peer EXchange (PEX for short) report a huge peer count because of all the ip addresses seen over the last 10+ days. Some VPNs and proxy connection internet exit points may change too.

Or it could be a bunch of fake peers, put up by "poisoners" or monitoring groups. (Google if you want to know more...)

All it takes is 1 peer, seed, or tracker incorrectly reporting every ip ever seen on the torrent over the last year or longer (instead of forgetting "old" inactive ips after awhile) to have this happen.

They go to error ...where did you see the error messages? Just the main window?
I get torrents going to error in qBT because/when I set qBT's cache too large.
Or file/folder permissions conflicts.
Or locked files. (in use by other apps...)
Or when I inadvertently delete the whole folder the files were in.

DHT alone is very unreliable -- it needs PEX with it typically combined with 10+ peers/seeds to stay "knit together" into a coherent torrent swarm.
Otherwise the peers and seeds may not find each other at all -- gotta love those dead tracker torrents that stay stuck at 0% complete.

The one with a "ton of trackers" has a bunch of trackers that aren't working period. Some of which have been dead for years. There's less than 10 working trackers in the pic, and of those probably 3-5 are duplicates of each other! Not going to get a lot of peers/seeds from them if 2P/2S is for the "busy" one.
uTorrent may get lucky connecting (through DHT nodes) to the 1 peer/seed that "sees" (via DHT and PEX) all the other working peers+seeds while qBT only gets the peers+seeds reported by trackers.

The second one has NO trackers. What happens when you fix that?
(...and get it to quit being queued by pausing some of your other torrents.)

So what was the status for the trackers on the 2 broken torrents?

No clue!

But you might want to delete all but the last 5 just for starters...

The slow upload speed can be due to private trackers with lots of seeds per peer, so that even if qBT connects to a peer it's "out-uploaded" by all the other seeds combined. A lone peer under those circumstances is often overloaded and cannot download very much from any individual seed.

On public torrents, many peers may have low-speed internet connections (even dial-up still!) and/or be throttled by their ISP. They might also have set their BitTorrent client such that it can't download quickly because others sharing the same internet connection have threatened them with harm if they keep hogging it all.

The questions I'd have to ask to determine the cause/s are:

1.Are you downloading torrents at the same time trying to upload? (download-induced overloads can murder upload speeds)

2.Are you testing using a single torrent that has few seeds but many peers? ...with other torrents either stopped or at least no connected peers+seeds?

3.Are you using a Proxy or VPN? (These sometimes silently change their policies on BitTorrent use, causing 'instant' speed losses. Their transit provider may throttle BitTorrent traffic even if they don't!)

4.What are your... qBitTorrent's general settings for max connections and max upload slots -- both globally and per torrent -- as well as other settings such as whether uTP is allowed or forced, half open connection max (>10 can cause overloads on poor networking equipment+software) all of which may have a huge influence on how well it can DL and UL.

5.Lastly, how fast is your download and upload supposed to be? What's the results you get when running speed tests? (include a link to the results if that's easy to do...)

Does qBitTorrent show that it is doing UPnP in its logger window? (You may need to enable that window to see it!)

It's grayed out possibly because you have a VPN/proxy and/or have checked "Disable connections not supported by proxies" or "Enable anonymous mode" in qBT.

"Are you absolutely certain I don't need UPnP and NAT-PMP?"

Absolutely yes.
https://www.privateinternetaccess.com/helpdesk/kb/articles/how-do-i-enable-port-forwarding-on-my-vpn
No mention there of UPnP.
UPnP is a poor substitute for manual port forwarding, if you know what port is needed in advance as well as what target ip (typically a LAN ip) the port is to be forwarded to.
It's likely qBT's UPnP will port forward the WRONG thing -- your modem/router combo box instead of the VPN.

"What benefit is it to disable these if the tracker has them disabled by default? Seems kinda irrelevant?"

DHT and probably LPD (LSD is same thing by a different name) are global networks in the sense that it doesn't matter if some or ALL of your torrents have DHT disabled on them.
DHT will run even if you have no torrents using it, connecting to probably 100's if not 1000's of ips per hour...on each BitTorrent client you have it running on.
LPD will do similarly and use either broadcast or multicast packets to do it. Even if the BitTorrent client handles these packets correctly, some networking hardware seriously doesn't:
https://forum.utorrent.com/topic/62993-lpd-multicast-flood-from-utorrent/

"How is there no seeds?"

Sorry, I wasn't even more wordy. I meant: "shows you connecting to ...no seeds."
Not connecting to isn't the same as there is no seeds. Seeds don't stay connected to other seeds -- often they don't even TRY to connect to other seeds, at least more than once.

"You consider those numbers to be low?"

No -- Many of the torrents I download have fewer than 10 reported and I'm lucky to connect to 4 out of 10.

"So 1 (1) Peers means 1 connected peer to another."

Not quite. 1 (1) Peers means 1 connected peer and (1 reported/possible/probable peer) -- it's even possible for the first 1 to not mean the same ip as the other (1)!