Currently the phase advances not only unlock new units, structures, and technologies, but also increase centre <TerritoryInfluence/Radius> and structure <Capturable/GarrisonRegenRate>.
Players who advance quicker are already at an advantage simply because the new things that are unlocked. These stat changes have a snowball effect, strengthening the stronger, and furthering the gap with those players that are slower, which seems rather undesirable.
Currently garrisoned structures are about 4× as hard to capture in the city phase as the same structures garrisoned by the same number of units are in the village phase.
This patch removes the structure capturable increases (previously 5 + 7 + 9 = 21 in city phase). To compensate, the default structure value is doubled (from 5 to 10) and territory decay is halved (from 20 to 10), because one garrisoned unit ought to be enough to prevent structure loss due to territory decay.
[EDIT] For the record, concerning <Capturable>:
rP10034 introduced territory health decay (of 20);
rP10048 sharply reduced territory health decay (to 5);
rP16550 introduced structure capturing (including <GarrisonRegenRate> of 3, soldier capture strength of 3) and replaced territory health decay with territory capture points decay (still 5);
rP16779 increased <GarrisonRegenRate> (to 5) and capture strength of champions (to 8);
rP16891 lowered capture strength of champions (to 7);
rP17053 increased <GarrisonRegenRate> (to 7.5) and lowered capture strength of citizens (to 2) and champions (to 5)
rP17564 increased capture strength of advanced (+0.4) and elite (+0.4) units;
rP17060 increased territory decay tenfold (to 50);
rP17062 reduced territory decay (to 20);
rP17077 lowered <GarrisonRegenRate> (to 4), but introduced increases in the town (+1.5) and city (+2) phases;
rP18157 increased <GarrisonRegenRate> to current values (5 + 7 + 9).