Ender pearl elevator not working.

Does it work in 1.15.2? This could be related to fixes done for block lag with pistons

Works on 1.15.2.

Atm I cannot confirm (am only on mobile).
In case what OP wrote is true:
Potentially due to fix of MC-73884.
Fix-version for that was 1.16.2 pre-1.

Enderpearl elevators should still be possible, just potentially a tad trickier (got no time for testing).
I'm confident the tech community can find new ways, however, there could be a few other issues related to Enderpearls due to that change that I currently don't have on my radar, thus waiting for the community's feedback could be advisable.

Please check if that's still an issue for you in the latest 1.16.5 stable release or the latest 1.17 development snapshot.