Why don't you move to the dozens of instances that enable downvotes? Reddthat is literally one of the few instances that disable them (I know because I looked for them): https://github.com/maltfield/awesome-lemmy-instances?tab=readme-ov-file

You now can export and import your settings in two clicks in the settings menu, maybe you should consider moving elsewhere? Lemm.ee and sh.itjust.works are usually good choices