If you choose to run PHP 7.3, the following error may appear on your site:
JIT compilation failed: no more memory errors
This is a bug with PCRE which you can read about here:
To work around this bug, DreamHost automatically adds the following lines to your site's phprc file:
pcre.jit = 0
This setting accommodates the majority of all PHP websites. However, if you specifically need this enabled, you can adjust the setting to the value of 1 in your phprc file.