Straight from Via's media room, this is the expected timeline to return to full service on its network. 

Another quote from the release:

Quote

VIA Rail’s ridership dropped by more than 95% at the peak of the pandemic and although it is still down from our pre-pandemic levels, we are now seeing a steady demand, which explains the launch of this final phase. As such, VIA Rail will add frequencies while continuing to employ a balanced approach, in order to fulfill its public service mandate and manage financial impacts. Because of the pandemic, many regions have had limited access to transportation and this plan for returning to full service will allow VIA Rail to offer more options. [...] VIA Rail continues to deploy strict protocols of sanitary measures on board its trains, in its stations, maintenance centres, call centres and offices to deal with the pandemic and minimize the spread of COVID-19. Teams across the organization also continue to apply the latest health and safety guidelines and are evaluating VIA Rail’s overall service offering in the context of the pandemic.

Obviously, no real service increase there beyond what was there pre-pandemic, I assume this will be dictated by the new rolling stock arriving on the Quebec-Windsor corridor starting 2022.

In the topic of "service updates".

VIA RAIL UNVEILS ITS MANDATORY VACCINATION POLICY

VIA Rail Canada (VIA Rail) is unveiling its mandatory vaccination policy in line with the regulations outlined today by Transport Canada. Via Rail’s comprehensive vaccination policy will require everyone 12-years of age and older on board our trains to show proof of vaccination as of October 30.

To allow passengers time to become fully vaccinated, there will be a one-month transition period during which passengers will be able to travel if they show a valid COVID-19 molecular test within 72 hours of travel time. This transition period will end on November 30, after which all passengers must be fully vaccinated in order to board our trains. For full details on VIA Rail’s mandatory vaccination policy, as well as all other COVID-19 measures please visit our website.

Key Dates:

• October 30 – Passengers 12-years and older boarding VIA trains must show proof of vaccination or valid COVID-19 molecular test.
• November 30 – Passengers 12-years and older boarding VIA trains must show proof of full vaccination (COVID-19 molecular tests no longer accepted).

https://media.viarail.ca/en/press-releases/2021/rail-unveils-its-mandatory-vaccination-policy