This is a fallacy and I've showed you the numbers to prove it. If the grocery chains were gouging it would show up in their gross margin on sales which is the difference between what they sell a product for and the cost that they pay for it including shipping, waste etc.
From the Loblaw Companies Ltd. annual reports, this is their gross margin by year for the past 5 years
2019 29.7%
2020 29.5%
2021 30.7%
2022 30.9%
2023 31.0%
If there truly were price gouging that percentage would be well over 33%. But if you truly want them to get back to under 30% there needs to be more competition in the industry. Right now its operating as an oligopoly a few big players control 80+% of the market.
Loblaw Companies Limited own Loblaws, No Frills, Superstore, Zehrs, Shoppers Drug Mart, Provigo (QC), Fortino's, T&T Supermarket (30% of market share)
Empire Companies Ltd own Sobeys, IGA, Foodland, Safeway, Freshco, Farmboy, Longo's (51%) (21% of market share)
Metro Inc. owns Metro, Food Basics, Marche Adonis (QC), Jean Coutu (11% market share)
Costco (11% market share)
Wal-Mart (8% market share)
The other <20% market share would be the likes of Whole Foods, Giant Tiger, Dollarama, Rabba Fine Foods, Your Independent Grocer, Highland Farms etc.