Would Syncthing erroneously trigger throttling by my ISP?

I’ve got syncthing integrated into my workflow and it’s a handy tool for sharing data between peers in a remote work environment.

That said, I’ve noticed that my networking is really slow lately. Is there anything about how syncthing packages data during transfer that would make ISP think it was torrenting or some such?

You should ask your ISP what criteria they use to determine whatever throttling they do. If the criteria is “uploads data” and you do that, then yes, obviously. If the criteria is “speaks BitTorrent”, then no.

They actively deny that they throttle. it’s near impossible to prove.

If just your syncthing connections are slow, maybe you are using a relay.

Also check you are not saturating your upload bandwidth as that will make things slow due to delayed ACK’s .etc

for instance if you have a 20/2 connection try limiting sync-thing to 1.5Mbit/s upload.