Bundlesize is a useful for checking if a change results in a significant filesize increase, but setting the hard limits to the exact current filesize is often very frustrating for developers and not that useful. Using the tool like this will cause a V-1 even when the size increases by a few bytes, but will also miss more significant increases if the filesize dropped recently without the limit being decreased, e.g.
False positive:
FAIL skins.vector.styles: 9.31KB > maxSize 9.3KB (gzip)
False negative:
PASS skins.vector.search: 74B < maxSize 2.8KB (gzip)
(from https://gerrit.wikimedia.org/r/c/mediawiki/core/+/651848 )
The tool should be configured like a code coverage tool: reports should show % increases and warn if these are above a certain limit. If a fixed limit is desired, that should be a value that we would consider to be too high for some time to come, so it isn't expected to be continuously updated.