It is a combination of different things:

- the Alire crate system

- Nvidia's own usage of Ada

- lots of sleeping military projects that were awaken in recent years

- the success of Python which is strongly inspired by Ada

This might be the answer. It is not that the language became more popular, but rather the search keyword ada...

> This Month's Changes in the Index > William Herrera told us that programming language ADA might have been boosted in the TIOBE index because of the Ada Lovelace architecture of NVIDIA. For this reason we have added "-NVIDIA" to Ada's search term. As a consequence, Ada dropped from position #9 last month to position #13 this month.

Well, that will erroneously drop the ranking because NVIDIA themselves use the Ada programming language. Refer to:

https://nvidia.github.io/spark-process/

https://www.nvidia.com/en-us/on-demand/session/gtcsj20-s2112...

The term "Ada" appears in several contexts (sometimes for the same company) so keyword filters should not be used in such a simpleminded way.

Unfortunately the author of the TIOBE index has obeyed too quickly to what Mr Herrera told him. The hits about that "Ada Lovelace architecture" are a negligible part of the hits you get with: +"Ada programming" +"nvidia". The lions' share is about Nvidia's own usage of the Ada language. Those hits should be counted of course.