erasing is not synced to other participants properly

[HarHarLinks]

1. join a board as 2 people, A and B
2. as A, draw something
3. it appears on B's screen
4. as A, erase something
5. B's screen does not update
6. as A, draw something more where you previously erased
7. for B it appears that A is drawing over their own drawings

the only workaround i found is by refreshing the site and logging in anew, which isn't great because initial sync. this is over federation and B is using a chromium based browser.