There is an issue caused by Kaspersky (KAV, KIS and KTS) version 21.3.10.391(g) that, apart from some other web sites, prevents visitors of rainmeter.net main site and the forum to access it showing error code ERR_HTTP2_PROTOCOL_ERROR.
Until the "h" patch release for Kaspersky that's planned to be released from 31st of January till 14th of February, the affected users can avoid the issue in the next way:
As a workaround add the problematic sites to exclusions via Settings → Network settings → Trusted addresses → Add.
