I figured out the issue with the hash URL parameter being ignored by uBlock Origin: since hash includes item as its value, it gets excluded. Here is a temporary solution for that by using two static filters:
||ebay.*^$removeparam=~/(_nkw|_pgn|_sop|_ssn|action|blrs|cartid|_dmd|guestCheckoutEligible|ipg|item|itemId|itemid|LH_|sessionid|srt|token|transId|transid)/
||ebay.*^$removeparam=hash
Also, they include a wildcard, so all potential eBay TLDs (.com, .ca, .co.uk, com.au, etc.) are now affected by these rules.