Are the preset security levels available in previous releases removed?
No, what do You mean? in K2021 all the previous security settings are there, I even would say that there are additional and some new ones...
About setting K2021 to maximum I say it would affect probably system performance, as in any other security product, but if You run a search in Kaspersky section of this forum, You will find some threads where already this matter was discussed, also there are some
sticky threads in this section with tweaks
