MySQL 5.7.39 includes the following InnoDB changes:

Not applicable to MariaDB Server

BUG#33764808: UPDATE COPYRIGHT HEADERS TO 2022
This is updating the copyright year in thousands of source code files, not any other changes. We will update the Oracle copyright year only when importing changes from MySQL.
Bug #27325012 : SPACE MISSING IN OOS ERROR MESSAGE
This error message had been corrected as part of MDEV-15270 (MariaDB Server 10.2.13).
BUG #28934351 : INNODB: THE TABLE IS FULL ERROR ON INSERT BEYOND 4GB IN 32-BIT
This bug is basically a duplicate of MDEV-14887, fixing a regression that had been introduced in MySQL 5.7.6. Opening and extending data files has been refactored in MariaDB, so the code looks quite different. MariaDB tries to count sizes in pages, not bytes, and the number of pages is a 32-bit quantity. The byte quantities handled in fil_node_t::read_page0() and fil_space_extend_must_retry() already use a 64-bit type os_offset_t.

Because MariaDB Server 10.3 does not include a separate InnoDB version number (MDEV-16172), no code changes whatsoever will be necessary.