Don't know why a large female workforce would necessarily have to be considered as preferable over a limited one. It wouldn't be consistent with tradition nor, in practice, with Islamic rules considering the structure of contemporary society. It would leave women with less time to tend their children and homes.
Moreover - and this should be of relevance to less religious people as well, Iran is suffering from an demographic downturn so intense that it represents an existential threat to the Iranian nation. And generalized female labor could only worsen the problem.
Figures from other countries do not contradict this reality. Some nations simply have a more dynamic demography to boot. All it means is that if female participation in the labor market was lower in those countries, then other things being equal their fertility rate would've been higher still, compared to its present level.
As said fertility is affected by a multiplicity of factors, not just by the percentage of females working. But once it drops below generational replacement limit as is the case of Iran, the concerned nation will be facing an huge and urgent challenge. At that point you better not compound the dilemma by sending females to work.
In line with this I must repeat: the figure for Iran in that chart is incorrect. Reality is that Iran's fertility rate in 2021 stood at a flimsy
1,71. Reminder: replacement threshold is 2,1 at minimum. The Supreme Leader keeps warning and warning about the issue.
Here's a relevant source:
Iran’s Supreme Leader has encouraged officials to continue the work of increasing the birth rate, but that is a challenge even in economically prosperous countries.
www.al-monitor.com
Demographic ageing brings with it a whole slew of economic calamities of its own.