Looks like the wiki TABLE BB-Code has been renamed automatically. This bug appeared in 4.1.0 Beta 4.
Fixed in the next build. While we intend to ignore any BB-Code name conflicts for existing wiki tags, this was not working correctly for the TABLE tag, which has an XF 2.1 conflict that doesn't exist in the xf_bb_code table.
You should be able to restore the previous functionality by going into AdminCP > Content > Custom BB Codes, and editing the TABLE BB-Code so its tag name is "table" again.