Different Versions of InDesign found different GREP search results

You are matching a pretty gnarly sequence of returns, tabs and escaped HTML. The key is to normalise the line breaks and the <br> tags so the pattern stops relying on exact ASCII escape sequences that 2025 seems to interpret differently.

This might be a more robust GREP pattern that should match the same structure but tolerate slight variations:

\r\t\r(?:<br\s*\/>\s*){4}\r\n<p style="text-align:\s*center;"?><strong>

If you want it even stricter:

\r\t\r(?:<br\s*\/>){4}\r\n<p style="text-align: center;"><strong>

If you want it more forgiving:

\r\t\r(?:<br\s*\/>\s*){3,5}\s*<p[^>]*text-align:\s*center[^>]*><strong>

If you paste in a small sample of the actual text block you are matching the pattern can be tuned even further so it is consistent across 2024, 2025 and 2026.