I think what ender means is that if you're in save mode, once you FIRE, things you had locked down/highly structured are no longer so.
You may not be able to add to retirement accounts (I'm not familiar with Canada's rules, but in the U.S. requires earned/working income to add to retirement accts) so that bucket may be good to repurpose for the buckets that go up. If you plan to have zero mortgage payments, the only other thing I think you're missing is home repairs/maintenance (home/yard upkeep will need a category as you'll likely need to repair/replace/maintain your house, things like the water heater dies, air filters, mowing/snow clearing, or roof type stuff)
Based on my own FIRE:
vacation expenses may go up since you'll have more time/freedom to go more often and stay longer
food expenses - both at home or eating out - as you may enjoy cooking more meals/trying new recipes, or dining out more often (we have breakfast/brunch, lunch and dinner as possible depending on what we're doing and if anything strikes our fancy while doing things out and about)
entertainment may go up - ability to go to weekday events, concerts, movies, theater, etc... last minute fun things that cost $ aren't really an issue unless you just don't feel like going. Hobbies may add to expenses depending on what you're into.
utilities may go up if you're a homebody - using more water/flushing the toilet, lights and heat/AC on more, watching tv, etc....
Retirement expenses can get lumpy since there isn't as much structure and you don't have to do anything really other than basic bills to live. You may have no problems moving your mortgage/work commuting bucket to cover the new/lumpy expenses tho.