jee criteria jo tha 75 per board wala wo sirf iss year k liye haataaya hai kyaa

There is no such criteria to be eligible for Jee Main. There is no percentage barrier at all. You just only need to qualify your intermediate with Physics, Chemistry and Mathematics along with English from a recognizer board. This 75% marks criteria is for admission to NITs and IIITs and CFTIs and to be eligible for Jee Advanced.
Along with qualifying Jee Main, there is another criteria for being eligible for Jee Advanced and that is the candidates must have secured at least 75% aggregate marks in Class 12. 5% relaxation in marks for reserved categories. But this year it's different. As all the subjects of class 12 of several boards have not conducted and marks have been provided on the basis of internal assessment and previous exam marks, many students have affected by these. So this year, the criteria of at least 75% or top 20 percentile has been withdrawn only for this years. So there is no percentage barrier for admission to NITs and other Centrally funded Technical Institutions and also for Jee Advanced. The candidates who will clear the Jee Main qualifying cutoff will be eligible for Jee Advanced.
This is only for this year. For next year till now there's no update about that. The authority will think about that based on the situation then.

Yes, That is for this Year only.

There is no announcement for the next Year. It might change and they will announce accordingly.

You can also check the Detailed Article at: -

https://news.careers360.com/jee-main-2020-eligibility-criteria-reduced-for-nits-and-cftis-hrd-minister#:~:text=According%20to%20JEE%20Main%20eligibility,admission%20into%20NITs%20or%20CFTIs.