Upgrading and downtime

On reddit someone wrote:

You can’t use something like Logical Replication to have a seamless and (almost) zero downtime upgrade.


Is this still true? I couldn’t find something about upgrade downtime on the website. Does this apply to both postgres and timescaledb-plugin upgrades?

Does anyone know if this is different for InfluxDB? Like with Timescale, I wasn’t able to find anything in the docs there.