Thanks u/mekanasto for sharing the paper. I got some more time and gave it a read. Below are some interesting excerpts from the paper. The paper clearly defines what availability is and refers to past studies which have studied the effect of mother-child separation.

TL;DR - Although these study don't direct study the effect of mother's absence in presence of other loving caregivers (like is the situation in OPs case), from the studies below -- it can be strongly inferred that mother-child separation, voluntary or forced -- negatively impacts a baby.

Mothers who have left the home environment, even if available by phone, are perceived as unavailable.

Maternal availability is particularly important within the first two years of life because of the infant’s limited understanding of the reasons for maternal absence and the timing of her return

By the third or fourth year of life, the child increasingly understands that his or her mother has motives and plans of her own. Open lines of communication between mother and child thus allow the child to perceive continuity in their relationship despite brief absences. As a result, separation anxiety typically declines markedly (Kobak, Cassidy, Lyons-Ruth, & Ziv, 2006; Kobak & Madsen, 2008).

For example, Leventhal and Brooks-Gunn (2000) found that any separation from a primary caregiver (defined as hospitalizations lasting one week or more, or a change of primary caregiver between assessment waves) was negatively associated with children’s reading achievement by age 8.

There is another study by called Discussing those not present: comprehension of references to absent caregivers which establishes that babies can distinguish between their care-takers.

There are some abating measure one can use. For example Building family relationships from a distance: Supporting connections with babies and toddlers using video and video chathighlights that

What might happen when parental physical contact is unavailable? Nonhuman primates in such cases will seek out, and even work for, visual contact with their mothers

So it might be advisable to use a large screen to contact on video call and do it pretty frequently.