Some common crawl budget optimization mistakes include not optimizing your crawl budget, not using robots.txt file properly, not using sitemap.xml file properly, not using canonical tags properly, not using hreflang tags properly and not fixing broken links ¹.

Source: 
(1) 7 Tips to Optimize Crawl Budget for SEO - Search Engine Journal. https://www.searchenginejournal.com/technical-seo/crawl-budget/
(2) How to optimize your crawl budget • Yoast. https://yoast.com/crawl-budget-optimization/
(3) Crawl Budget Optimization: Stop Wasted Crawl Budget | Victorious. https://victoriousseo.com/blog/crawl-budget-optimization/