Multisite table wp_sitemeta grows huge – currently 27.82 GB

I’ve noticed my multisite has been growing huge in size and this month I can’t optimise the wp_sitemeta table like I have done before to reduce it.

The table is 28 GB.

I am not sure if it’s related to the wild table growth, but one of the subsites I can’t see the media library because it just hangs.

Thanks in advance for any help.