Table of content does not work with the new update

After the last update to the Colormag theme, the Table of Content feature I used with the Ultimate Blocks plugin stopped working. The problem was resolved when I reverted the theme to its old version. There is no problem when adding the Table of content to new posts or manually updating it in old posts. But I have a lot of writing and I won’t fix it one by one. I will be using the old version for a while (until the problem is resolved). Here is an archived version of a page with this error: https://web.archive.org/web/20210404092241/https://ridvanatmaca.com/vpn-nedir-en-iyi-vpn-servisleri/

I will also contact the plug-in support regarding the problem, but the problem is due to the theme. Because it happened after the update.