Release 2021_040 is ready and will be rolled out during the specified timeframe. This will be the last planned release for this year and includes additional fixes for the log4j2 vulnerability. Other fixes for that have already been rolled out before.
See the Changelog
for information about the specific changes and impact of the release.
Note: releases themselves do not cause downtimes. If a change within a release requires downtime then every VM that is affected will schedule a maintenance period according to your projects' preferences and notify you with specific details about the downtime.
Check the "Impact" section of the changelog (linked above) to see potential causes of downtimes in a release.