Both scripts use Mutation Observers, which probably results in an endless loop of DOM updates.
Sadly the Mutation Observer API is limited.
It is not possible to stop Mutation Observers from observing DOM insertions unless you have the actual Mutation Observer object and disconnect it before the insertion.
It is not possible to get all currently active Mutation Observers for the document or an element.
To fix this collision, the selector strings have to stop matching elements added by the scripts.
In the worst case changes to StashDB Backlog Userscript might be required.
A user reports the browser hanging up when both userscripts run on the same site. Browser: Edge Addon: Tampermonkey
See StashDB Backlog Userscript
Both scripts use Mutation Observers, which probably results in an endless loop of DOM updates. Sadly the Mutation Observer API is limited. It is not possible to stop Mutation Observers from observing DOM insertions unless you have the actual Mutation Observer object and disconnect it before the insertion. It is not possible to get all currently active Mutation Observers for the document or an element.
To fix this collision, the selector strings have to stop matching elements added by the scripts. In the worst case changes to StashDB Backlog Userscript might be required.