No doubt a corroded landing gear trunk on which is a known inspect and repair item. Definitely negligent maintenance practice by Westjet IMHO.
I wouldn’t be flying that airline home
"No doubt...definitely...?" That's pure speculation and armchair quarterbacking. Let's wait until the TSB report comes in. Maintenance mistakes can and do happen, but WestJet is Canada's second largest carrier. There have not been a spate of problems due to serious maintenance issues reported nor experienced, so any maintenance issues are obviously not widespread. I have been flying them to SXM every year for about the last 12 years, and will be doing so again in January.