What are all of the ways to raise/lower a city's loyalty?

Question

What I know,

• Settling too close to another civilization can drop the loyalty of a new city.
• As Lautaro's Mapuche you can kill enemy units near their cities to lower their loyalty.
• Governors affect a city's loyalty (not sure in what regards fully yet).

What are all the ways a city's loyalty can be raised and lowered so that I (and others) may form strategies around this mechanic?

Answer 1

Loyalty is improved in the following ways (Will add more as I find them),

• Each population provides 1.0 loyalty up to 9 tiles away but are 10% less effective for each tile away.
• Heroic/Golden Ages add 0.5 loyalty per population.
• Dark Ages remove 0.5 loyalty per population.
• Governors established in the city emit +8 loyalty (some can be promoted for more) and other civilizations' governors in nearby cities can reduce your cities' loyalty.
• The happiness level (Amenities) of your city affects loyalty.
• The Limitanei military policy card provides +2 loyalty in a city with a garrisoned unit.
• The city-state Preslav provides +2 loyalty in cities with an Encampment district when Suzerian.
• There are two city projects that can increase loyalty when complete (Break and Circus projects).
• Culture alliances with other civilizations can prevent negative loyalty effects from population of that civilization.
• Recently captured cities (through military) will have loyalty penalties, but these can be ignored with a garrisoned unit inside.
• The Audience Chamber building in the Government Plaza district applies a -2 loyalty penalty to every city without a governor (Thanks to David Harkness).

I found this information in-game on the city panel (loyalty page).