MySQL 5.7.35 includes the following InnoDB changes:

Applicable to MariaDB Server

Bug #32460315 ONLINE RESIZING BUFFER POOL CAN CRASH CONCURRENT BP LOOKUP
In MDEV-26033 (10.5.12, 10.6.3), this was fixed differently, by never resizing the hash table. This fix should be applicable to 10.2, 10.3, 10.4. There is no test case.

Bug #31576731 INNODB_FT_TOTAL_CACHE_SIZE NOT CAPPED WHEN SET TO 32000000
There is no test case, but the change looks reasonable.

Bug #32507117 INDEX SIZE LARGER THAN 767 BYTES ALLOWED FOR INNODB WITH REDUNDANT ROW_FORMAT
Covered by MDEV-26203.

Not applicable to MariaDB Server

backport Bug#31060470 to 5.7 Bug#31060470 : InnoDB temp table could hurt InnoDB perf badly (Bug#98974)
MDEV-12227 fixes this in a simpler way, but only starting with 10.5. It is not worth the risk and effort to port the fix to 10.2, 10.3, 10.4.

Bug #32757201 FIX GCC 11 BUILD WARNINGS IN 5.7 (2)
We will evaluate and fix GCC 11 warnings on our own. The fixes look a little suboptimal; the custom InnoDB memory allocation functions cannot really return a null pointer.

Bug #29747853: UPGRADE THE BUNDLED LZ4 LIBRARY TO THE LATEST VERSION
An unsafe call to LZ4_decompress_fast() was already removed in MDEV-13103. MariaDB does not bundle the LZ4 library.

Bug #32800020 EXPLORATORY - INVESTIGATE ODD NON-DATA DEADLOCK
MariaDB never changed the rollback segment format in a way that is incompatible with older versions (MDEV-12289).

To be determined

Bug #30556595 FAILING ASSERTION: !CURSOR->INDEX->IS_COMMITTED() ON TABLE WITH GCOLS
The test case does not fail on MariaDB, and it is returning the expected result. Update: The test innodb.virtual_index also passes on MySQL 5.7.35 with and without the code change!

Bug #30215068 BINLOG ROTATION DEADLOCK WHEN INNODB CONCURRENCY LIMIT SETTED
This is related to statement-based replication and innodb_thread_concurrency, which is disabled by default and was deprecated and ignored in MariaDB Server 10.5 (MDEV-23379).