The limitations of GA4 reports are that GA4 allows 25 user-scoped custom dimensions, 50 event-scoped custom, and 50 custom metrics for each property.
A workaround for this is to use Whatagraph for GA4 reporting. Whatagraph is a marketing data platform that has a ready-made connection with GA4 API, and all data transformations take place within Whatagraph. In other words, you can create as many custom metrics and dimensions as you need.
With Whatagraph, you can effortlessly combine metrics from multiple data sources, like Google Ads and Google Search Console, and create custom reports for cross-channel campaigns from one place.