The release was rolled out last Friday. According to the changelog from PHP.net, it contains fixes for many issues  – 8 resolved in 8.0.17 and 14 addressed in 8.1.4 (mostly related to the Core). 

Both versions contain some common fixes, such as:

• Fixed Haiku ZTS build;
• Resolved issue in libpng causing warnings when loading interlaced images;
• Resolved issues with unsafe access to the fpm scoreboard;
• Resolved issue with ob_clean() not setting content-encoding;
• Resolved issue with unexpected output for iconv_mime_decode;
• Resolved issue causing NULL pointer dereference for MySQLnd;
• Resolved issue with ReflectionClass::getConstants() depending on the order of constants definition.

One fix is related to 8.0.17 only:

• Resolved issue with incorrect type inference for range() results.

And seven are related to 8.1.14:

• Resolved issue with arginfo not re-generated for extension;
• Resolved issue with segmentation fault caused by dumping uncalled fake closure containing static variables;
• Fixed leaking memory when using nested CallbackFilterIterator;
• Fixed leaking memory when using op_arrays with temporary run_time_cache;
• Resolved issue with incorrect types in the output of range();
• Resolved issue with First Class Callable Syntax causing Uncaught ArgumentCountError;
• Resolved issue causing incorrect results while using mb_check_encoding for 7bit.

PHP team recommended the developers upgrade their environments and use this version.