Here's what worked for me: Go to Settings>Keyboard>Text Replacements... on your Mac (Ventura in my case), "select all", right-click and 'Export' the list to your desktop/downloads (wherever you like). Now, delete all of them.
Right click again and 'Import' the list you just exported. This immediately sent all of them back to my phone.
I tried this after realizing that when I created a new text replacement on my iPhone, it immediately showed up on my MacBook. I then created one on my MacBook that immediately showed up on my iPhone. So, after weeks of frustration, I now have all my (years worth of) text replacements back on my iPhone. Thanks Apple..... 🤨