If you look at pgn-viewer, there are quite a few bugs and feature requests that have never gotten resolved. I ran into one just now in an answer I posted. The last update to the code repo (https://github.com/andrewphoy/chess-replayer) was 7 years ago and seems abandoned.
I propose using the new lichess embedded pgn viewer (https://github.com/lichess-org/pgn-viewer) instead, to get a more featureful viewer while still being lightweight.
However, the previous viewer was MIT licensed while this is AGPL-3.0. I'm not sure what the Stack Exchange policy for embedded content is.